1. Field of the Invention
The application relates to a method utilized in a wireless communication system and a communication device thereof, and more particularly, to a method of handling measurement capability in a wireless communication system and a related communication device.
2. Description of the Prior Art
A long-term evolution (LTE) system, initiated by the third generation partnership project (3GPP), is now being regarded as a new radio interface and radio network architecture that provides a high data rate, low latency, packet optimization, and improved system capacity and coverage. In the LTE system, an evolved universal terrestrial radio access network (E-UTRAN) includes a plurality of evolved Node-Bs (eNBs) and communicates with a plurality of mobile stations, also referred as user equipments (UEs).
In the LTE system, a user equipment (UE) may perform measurement to measure communication quality, such as quality of a frequency layer or strength of a radio signal, which is controlled by the E-UTRAN, due to mobility of the UE. Measurement can be divided into two types according to the current operating frequency of the UE, which are an intra-frequency measurement and an inter-frequency/inter-RAT measurement. The intra-frequency measurement is predominantly performed for the mobility within the same frequency layer (i.e. between cells with the same carrier frequency), whereas the inter-frequency/inter-RAT measurement is predominantly performed for the mobility between different frequency layers (i.e. between cells with a different carrier frequency). In addition, the inter-frequency/inter-RAT measurement is performed during uplink/downlink idle periods, such as a measurement gap configured by the network. During the measurement gap, both the uplink and downlink transmissions are prohibited, and thereby the inter-frequency/inter-RAT measurement can be performed within the measurement gap.
Toward advanced high-speed wireless communication system, such as transmitting data in a higher peak data rate, LTE-Advanced system is standardized by the 3rd Generation Partnership Project (3GPP) as an enhancement of LTE system. LTE-Advanced system targets faster switching between power states, improves performance at the cell edge, and includes subjects, such as bandwidth extension, coordinated multipoint transmission/reception (COMP), uplink multiple input multiple output (MIMO), etc.
For bandwidth extension, carrier aggregation is introduced to the LTE-Advanced system for extension to wider bandwidth, where two or more component carriers are aggregated, for supporting wider transmission bandwidths (for example up to 100 MHz) and for spectrum aggregation. According to carrier aggregation capability, multiple component carriers are aggregated into overall wider bandwidth, where the UE can establish multiple links corresponding to the multiple component carriers for simultaneously receiving and/or transmitting.
In addition, COMP is considered for LTE-Advanced as a tool to improve coverage of high data rates, cell edge throughput, and system efficiency, which implies dynamic coordination among multiple geographical separated points. That is, when an UE is in a cell-edge region, the UE is able to receive signal from multiple cells, and the multiple cells can receive transmission of the UE.
However, in the LTE system, measurement functionality is defined for the UE supporting a single component carrier. The network always configures a measurement gap to the UE for the inter-frequency/inter-RAT measurement. For the UE operated in the LTE-Advanced system, the measurement functionality is not clear defined for the UE supporting multiple component carriers. Improper configuration of the measurement gap may cause packet scheduling problems. Since data transmission/reception cannot be performed during the measurement gap, transmission/reception performance of the UE is downgraded.
In addition, consider a scenario related to multimedia broadcast multicast service (MBMS). The MBMS gives the opportunity to broadcast or multicast TV, film, information such as free overnight transmission of newspaper in digital form and other media in these networks. Since the MBMS is a broadcast or multicast service, the network is unable to know which one of the UEs receives the MBMS data when the MBMS is provided by the network. This causes difficulty in measurement gap configuration for the network.